From: Richard Biener <rguenther@suse.de>
Date: Tue, 6 May 2014 14:22:41 +0000 (+0000)
Subject: backport: re PR tree-optimization/57417 (hang on volatile int array)
X-Git-Tag: releases/gcc-4.7.4~116
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cb8d7dad6485ff43bcca48cedbc7a6064080c792;p=thirdparty%2Fgcc.git

backport: re PR tree-optimization/57417 (hang on volatile int array)

2014-05-06  Richard Biener  <rguenther@suse.de>

	Backport from mainline
	2013-05-27  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/57417
	* tree-ssa-sccvn.c (set_ssa_val_to): Compare addresses using
	get_addr_base_and_unit_offset.

	* gcc.dg/torture/pr57417.c: New testcase.

From-SVN: r210110
---

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index a5390e67db0e..030f3ffcd74d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2014-05-06  Richard Biener  <rguenther@suse.de>
+
+	Backport from mainline
+	2013-05-27  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/57417
+	* tree-ssa-sccvn.c (set_ssa_val_to): Compare addresses using
+	get_addr_base_and_unit_offset.
+
 2014-04-25  Eric Botcazou  <ebotcazou@adacore.com>
 
 	PR target/60941
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index e58454589f0a..6b5f1f576203 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2014-05-06  Richard Biener  <rguenther@suse.de>
+
+	Backport from mainline
+	2013-05-27  Richard Biener  <rguenther@suse.de>
+
+	PR tree-optimization/57417
+	* gcc.dg/torture/pr57417.c: New testcase.
+
 2014-04-25  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* gcc.c-torture/execute/20140425-1.c: New test.
diff --git a/gcc/testsuite/gcc.dg/torture/pr57417.c b/gcc/testsuite/gcc.dg/torture/pr57417.c
new file mode 100644
index 000000000000..6eac6f932b81
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/torture/pr57417.c
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+
+int a, b;
+volatile int *c;
+
+void foo ()
+{
+  volatile int d[1];
+  b = 0;
+  for (;; a--)
+    c = &d[b];
+}
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c
index c2bd59d6416d..1e4dc14434d6 100644
--- a/gcc/tree-ssa-sccvn.c
+++ b/gcc/tree-ssa-sccvn.c
@@ -2483,6 +2483,7 @@ static inline bool
 set_ssa_val_to (tree from, tree to)
 {
   tree currval = SSA_VAL (from);
+  HOST_WIDE_INT toff, coff;
 
   if (from != to)
     {
@@ -2518,7 +2519,17 @@ set_ssa_val_to (tree from, tree to)
       print_generic_expr (dump_file, to, 0);
     }
 
-  if (currval != to  && !operand_equal_p (currval, to, OEP_PURE_SAME))
+  if (currval != to
+      && !operand_equal_p (currval, to, OEP_PURE_SAME)
+      /* ???  For addresses involving volatile objects or types operand_equal_p
+	 does not reliably detect ADDR_EXPRs as equal.  We know we are only
+	 getting invariant gimple addresses here, so can use
+	 get_addr_base_and_unit_offset to do this comparison.  */
+      && !(TREE_CODE (currval) == ADDR_EXPR
+	   && TREE_CODE (to) == ADDR_EXPR
+	   && (get_addr_base_and_unit_offset (TREE_OPERAND (currval, 0), &coff)
+	       == get_addr_base_and_unit_offset (TREE_OPERAND (to, 0), &toff))
+	   && coff == toff))
     {
       VN_INFO (from)->valnum = to;
       if (dump_file && (dump_flags & TDF_DETAILS))